Supporting arm assembly for a driving wheel of an automotive vehicle

ABSTRACT

An oscillating supporting arm assembly for the driving wheel of a motorcycle, includes an arm mounted to oscillate angularly about a connecting shaft of the motorcycle and cooperating with a suspension assembly between the arm and motorcycle, the wheel being removably fixed to a supporting shaft on one side of the free end of the supporting arm, the supporting shaft extending through the arm on two bearings, a wheel driving pinion is fixed to the supporting shaft, on the side of the arm opposite to the wheel and is driven by a chain mechanically connected to the driving assembly of the motorcycle, the supporting arm having the configuration of a U with two legs between which the rim and the tire of the rear wheel are located, one of the legs having hinge connections which cooperate with the connecting shaft of the motorcycle, the wheel has its median plane extending at substantially equal distances from the two hinge connections of the supporting arm, the wheel is rigidly connected to a brake disc cooperating with brake tightening mechanism fixed to the supporting arm and wherein the brake disc is mounted substantially on the longitudinal axis of the motorcycle coinciding equally with the transverse median plane of the wheel so as to limit the torsion of the supporting arm and the reactions to the braking forces.

BACKGROUND OF THE INVENTION

The present invention relates to a supporting arm for the driving wheelof a vehicle comprising a suspension which oscillates by an angularmotion of the arm about an axis connecting it to the body of thevehicle.

Suspensions of this type are now currently used in automotive vehicles,and the driving wheel is usually rotated by means of a shaft extendingthrough the supporting arm and connected to a driving organ through acardan or homocinetic joint allowing it to absorb the angularoscillations of the arm, which bring about variations of the length andthe inclination of the shaft.

When it is desired to apply such a driving wheel suspension to a motorcycle, a solution is generally proposed, which consists in connectingthe wheel to a supporting shaft mounted onto the arm by means ofbearings, said supporting shaft being integral with a conical toothedcrown wheel which is mechanically connected to the driving motor througha shaft supported by the arm and integral, in turn, with a conicalpinion which meshes with the conical crown wheel.

An assembly of this kind is reliable, but the mechanical connectionsbetween the motor and the driving wheel are difficult to achieve andexpensive.

It is thus one of the objects of the invention to provide a motor cyclerear driving wheel suspension assembly comprising a rotative supportingarm, this driving wheel being adapted to be driven by a chain, whichconstitutes up to now the most simple and reliable driving means forbicycles and motor cycles, since it is able to undergo comparativelylarge offsets and variations of the distance between the axes.

SUMMARY OF THE INVENTION

To this end the invention provides a rotative supporting arm assemblyfor the driving wheel of a vehicle, such as the rear suspension arm of amotor cycle, which is adapted to oscillate angularly about a connectingaxis integral with the body or frame of the vehicle, so as to cooperatewith suspension and/or damping means with a view to suspending the bodyor frame of the vehicle with respect to the wheel, said wheel beingfixed, on one side of the supporting arm in an easily removable manner,by any convenient means, such as a fixing bolt or screw, to a supportingshaft extending through said arm on two bearings having a high rigidity,such as conical roller bearings, while a wheel driving pinion is fixedonto the supporting shaft, on the other side of the arm, so as to alloweasy dismounting of the wheel on the side of the supporting arm withoutacting on the wheel driving means, said driving means not being locatedin said arm and consequently not increasing the space requirementthereof said supporting arm having the general configuration of a U,said wheel having an enveloping cross section with respect to thesupporting arm, so as to allow the rim and the tire of said rear wheelto be located within the branches of the U, while providing a sturdyhinging connection with the vehicle body, said wheel being mounted, asknown per se, in such a manner that its median plane extends atsubstantially equal distances from two hinge bearings connecting thesupporting arm to the connecting shaft which is locked with the vehiclebody, so as to limit the torsional moment of the arm under the effect ofthe reaction forces applied to it by the wheel.

The wheel--at least when fixed to the supporting shaft--may be fixed toa brake disc cooperating with a brake disc clamping or tightening organ,such as a brake yoke, which is fixed to said supporting arm. In amodified embodiment the brake disc is fixed to the wheel supportingshaft, and the wheel is fixed to the hub of the brake disc.

According to another embodiment of the supporting assembly according tothe invention, two bearings having a high rigidity and supporting theshaft which carries the wheel and the driving means are rigidly lockedto a mounting bore provided in said arm, by means of a lateral slot ofthe arm, which opens into said bore and the two edges of which areadapted to be brought near to each other by preferably adjustabletightening means, such as a tightening or clamping collar, or at leastone screw or bolt extending through said slot.

IN THE DRAWING

Other object, advantages and features of the invention will becomeapparent from the following description of an embodiment of theinvention, referring to the appended drawing, and given by way ofillustration, but not of limitations.

The single FIGURE of the drawing shows, in section and viewed fromabove, the supporting arm assembly of the rear driving wheel of a motorcycle.

DETAILED DESCRIPTION

The supporting arm 1 is connected by bosses 2 and 3 to the housing 4 ofthe motor of a motor cycle by means of a connecting shaft 5 whichextends through corresponding bosses of said housing. Connecting shaft 5is held in its position with respect to housing 4 by any convenientmeans, such as a circlip 6 associated with an abutment provided on apinion shaft and cooperating with one lateral face of the bosses 7 ofhousing 4.

Viewed from above, as shown, supporting arm 1 has the generalconfiguration of a U, so as to allow the rim and the tire of the rearwheel 8 of the motor cycle to be placed within the space defined betweenthe branches, or legs, of the U, while yet being hingedly, or pivotally,connected in a sturdy manner to housing 4 of the motor.

At its free end opposed to the hinged connection with shaft 5, arm 1 isprovided with bores 9 and 10 opening into each one of its lateral faces,one high-strength bearing, such as a conical roller bearing 11, 12 beingdisposed in each one of said bores and adapted to carry and guide asupporting shaft 13 which entirely extends through arm 1. On the leftside of the FIGURE shaft 13 is connected, by means of grooves 14 and aclamping screw 15, to wheel 8. Shaft 13 generally carries, on the leftside of the FIGURE, a flange 16 on which the hub 18 of a brake disc 19is fastened by means of studs 17 which, according to a particularembodiment, may also be used as wheel clamping studs.

The brake disc 19 is mounted substantially on the longitudina axis 20 ofthe motor cycle, which axis also coincides with the transverse medianplane of the wheel, so as to limit the torsion of arm 1 and thereactions to the braking forces. Disc 19 cooperates with a brake caliper21 which is attached to a mounting pad 22 integral with arm 1.

On the right side of the FIGURE supporting shaft 13 is fixed by aremovable flange 23 to a driven chain pinion 24 connected through anassociated chain 25 to a chain driving pinion 27 mounted in housing 4.Driving pinion 26 is substantially coaxial with respect to connectingshaft 5, so that during the angular (rotating) movements of supportingarm 1 about said axis 8, resulting from the oscillating motion of thesuspension assembly of the motor cycle, the distance between the axes ofchain pinions 24 and 26, respectively, will remain substantiallyconstant.

A lateral slot 28 allowing the tightening of the walls of bores 9, 10,respectively by means of a tightening or clamping screw 29, 30 forfirmly holding bearings 11, 12 opens into each one of bores 9 and 10containing said roller bearings 11 and 12. Furthermore, arm 1 carriesconnecting bosses 31, 32 adapted to be connected, respectively, to asuspension spring and a damping means (not shown), as well as a brakingpipe 33 connected to housing 4 by a flexible hose on account of theoscillations of the arm.

It will be understood by studying the FIGURE that under the combinedeffects of the load acting on wheel 8 and the reaction forces of thesuspension (not shown) arm 1 and wheel 8 are able to rotate aboutconnecting shaft 5, while all the reactions are applied to said shaft 5.Due to its U-shaped configuration the suspension arm entirely surroundsbrake caliper 21 and wheel 8, so as to reduce the space requirement ofthe rear part of the vehicle.

In the case of an incident concerning the wheel, such as a puncture, itis only necessary to unscrew screw 15 so as to be able to withdrawimmediately wheel 8. After withdrawal of wheel 8 it is also possible topivot brake caliper 21, and to withdraw rapidly brake disc 19. Thisimproved accessibility of the wheel and the brakes is particularlyappreciable during racing competitions, but it also contributes toreduce the maintenance expenses for ordinary vehicles. It is furtherpossible to withdraw driven chain pinion 24 from the associated mountingflange 23 by unscrewing the fixing screws or bolts attaching said pinionto said flange. Driven pinion 24 may be mounted in its working positionwhile chain 25 is engaged on both chain pinions 24 and 26, whereby theassembling operation is facilitated and any chain tightening problemsare eliminated. It should be noted that the supporting arm assemblyaccording to the invention operates correctly when pinion 26 is notdirectly coaxial with respect to connecting shaft 5, but is, forexample, mounted coaxially with respect to an intermediary pinion 34. Inthese conditions the chain 25 need only be mounted with a normal slackwhile being able to absorb not only any axial offset, but also theslight variations of the distance between the axes which occur onaccount of the limited rotation of arm 1 about connecting shaft 5.

The invention is not limited to the embodiments shown and describedherein-above; many variants and modifications may be envisaged by thoseskilled in the art without departing from the spirit and scope of theinvention as defined in the appended claims.

What is claimed is:
 1. An oscillating supporting arm assembly for thedriving wheel of a motorcycle, comprising an arm mounted to oscillateangularly about a connecting shaft of said motorcycle and cooperatingwith suspension means .[.between said arm and motorcycle.]., said wheelbeing removably fixed to a supporting shaft on one side of the free endof the supporting arm, the supporting shaft extending through said armon .[.two bearings.]. .Iadd.bearing means.Iaddend., a wheel drivingpinion is fixed to the supporting shaft, on the side of the arm oppositeto the wheel and is driven by a chain mechanically connected to thedriving means of the motorcycle, said supporting arm having theconfiguration of a U with two legs between which the rim and the tire ofsaid .[.rear.]. .Iadd.driving .Iaddend.wheel are located, one of thelegs having hinge connections which cooperate with the connecting shaftof the motorcycle, .Iadd.wherein .Iaddend.said wheel has its medianplane extending at substantially equal distances from the two hingeconnections .Iadd.located at both ends of one leg .Iaddend.of the.Iadd.U-shaped .Iaddend.supporting arm, the wheel is .[.rigidly.].connected to a brake .[.disc.]. .Iadd.surface .Iaddend.cooperating withbrake tightening means .[.fixed to said supporting arm.]. and whereinthe brake .[.disc.]. .Iadd.surface .Iaddend.is mounted substantially onthe longitudinal axis of the motorcycle .Iadd.substantially.Iaddend.coinciding equally with the .[.transverse.]. median plane ofthe wheel so as to limit the torsion of the supporting arm and thereactions to the braking forces.Iadd., the supporting shaft extendingthrough the other free leg of the U-.Iadd.shaped arm on bearing meanslocated on said free leg between the wheel and the driving pinion, thewheel presenting an enveloping cross-section so as to mostly surroundthe free leg of the U-shaped arm.
 2. An assembly according to claim 1,wherein said wheel is mounted on the supporting shaft extending throughsaid arm, with a brake .[.disc.]. .Iadd.surface .Iaddend.cooperatingwith a brake tightening means, .[.such as a brake yoke.]. fixed to saidsupporting arm.
 3. An assembly according to claim 1, wherein said brake.[.disc.]. .Iadd.surface .Iaddend.is fixed to the supporting shaft, andsaid wheel is fixed to the hub of the brake .[.disc.]. .Iadd.surface. 4.An assembly according to claim 1, wherein the .[.two bearings.]..Iadd.bearing means .Iaddend.having a high rigidity and supporting thewheel supporting shaft are rigidly locked in a bore provided in saidarm, by means of a lateral slot of said arm, which opens into said boreand the edges of which are adapted to be brought near to each other byadjustable tightening means.
 5. The assembly of claim 4, wherein saidadjustable tightening means .[.comprises.]. .Iadd.comprise .Iaddend.atleast one bolt extending through said slot.
 6. The assembly of claim 4,wherein said adjustable tightening means .[.comprises.]. .Iadd.comprise.Iaddend.a clamping collar. .Iadd.
 7. An assembly according to claim 1wherein the supporting shaft is rotatably supported by two bearingsrespectively located in two bores respectively opening at opposite endsin the free leg of the U-shaped arm..Iaddend. .Iadd.8. An assemblyaccording to claim 1 wherein the bearing means are mounted on one sideof said median plane..Iaddend. .Iadd.9. An assembly according to claim1, wherein the bearing means are mounted on both sides of said medianplane..Iaddend. .Iadd.10. An assembly according to claim 1, wherein thebrake surface is a brake disc..Iaddend. .Iadd.11. An assembly accordingto claim 10, wherein the brake disc is mounted in the space between thewheel surrounding the free leg and the supporting shaft mounted in saidfree leg, said disc being connected to said wheel and said supportingshaft..Iaddend. .Iadd.12. A braking surface assembly for use with anoscillating supporting lateral arm assembly for a vehicle wheel, saidlateral arm being rotatably connected to a frame of the vehicle so as tocooperate with suspension and/or damping means, said wheel being fixedto a supporting shaft extending through said arm, on one side of thesupporting arm in an easily removable manner, a driving pinion fixedonto said supporting shaft, on the other side of the arm, saidsupporting arm having a general U-shaped configuration with a first legpivoted on the frame, the supporting shaft extending through the lengthof the second leg of the U-shaped arm, said wheel having an envelopingcross-section with respect to said second leg, so as to allow a rim andtire of said wheel to be located between the legs of the U-shaped arm,said braking surface assembly:(a). being mounted between the wheel andsaid second leg, (b) having an enveloping cross-section with respect tothe second leg and (c) being mounted to rotate with an assembly formedby the supporting shaft and the wheel fixed thereto..Iaddend. .Iadd.13.A braking surface assembly according to claim 12, wherein the brakingsurface includes a hub which is fastened on a flange carried by thesupporting shaft..Iaddend. .Iadd.14. A braking surface assemblyaccording to claim 13, wherein the braking surface is fastened to theflange by means of studs..Iaddend. .Iadd.15. A braking surface assemblyaccording to claim 14, wherein the studs are fastened on the flange andpass through the braking surface hub and through the wheel..Iaddend..Iadd.16. A braking surface assembly according to claim 15, wherein thewheel is clamped by the studs..Iaddend. .Iadd.17. A braking surfaceassembly according to claim 12, wherein the supporting shaft isconnected by means of grooves to the wheel..Iaddend. .Iadd.18. A brakingsurface assembly according to claim 17 wherein the shaft is connected bymeans of grooves to the braking surface assembly..Iaddend. .Iadd.19. Abrake disc assembly according to claim 10, wherein the brake disccooperates with a braking caliper which is pivotable after withdrawal ofthe vehicle wheel..Iaddend.